Allow Bouncer staging IP to configured in Hiera
Allow Bouncer staging IP to configured in Hiera

Unlike in `router::gor`, where the IP is hardcoded because it has
dependent `host` resources which would need to be purged manually`,
Bouncer does not receive traffic over SSL and so we can specify its
Staging IP in Hiera and change it as needed.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet